The best way to validate the environment is to build some code. Open the terminal in your Emscripten directory — the directory that contains emcc (if you installed using Github for Windows this will be C:/Users/username/Documents/GitHub/emscripten) and enter:

./emcctests/hello_world.cpp

If this builds a.out.js in the current directory, and you don’t see any build errors in the terminal, Emscripten is good to go!